Motor fuel



Patented Sept. 6, 1938 UNITED STATES PATENT OFFICE MOTOR FUEL No Drawing. Application September 27, 1935, Serial No. 42,511

16 Claims.

The present invention relates to a process and means for improving low boiling hydrocarbon fractions, especially hydrocarbon-containing motor fuels such as gasoline, kerosene, motor benzol,

or the like.

It is common knowledge that liquid hydrocarbon fuels produced on a commercial scale, and particularly those obtained from various crude petroleum oils by any of the well known processes of distillation, cracking or solvent extraction, contain gum or gum-forming constituents which are objectionable in many respects. The same may be said about motor benzol which is a hydrocarbon fuel derived from coal-tar and which contains 5 a large percentage of aromatic and unsaturated hydrocarbons. Gum or gum-forming tendencies of naphthas, gasolines, and similar low boiling hydrocarbon fractions is determined by the method No. 530.1 in the United States Bureau of Mines Technical Paper 3233, page 96, entitled "Specification for Petroleum Products and Methods of Testing," revised October 21, 1927. In brief, this method consists in placing 100 c. c. of the liquid hydrocarbon to be tested in a spun copper dish about three and one-half inches in diameter ona steam bath, and evaporating off the volatile material. The result is expressed as milligrams of gum left in the dish per 100 c. c. of gasoline, naphtha or similar low boiling fractions.

The presence of gum-forming constituents is especially pronounced in the case of gasolines produced by any of the well known cracking processes. Although such gasolines constitute excellent motor fuels from an anti-knock standpoint,

they are objectionable in view of the fact that they contain or develop large amounts of gum on storage, and/or tend to deposit gum in various parts of an internal combustion engine, thus interfering with its emcient operation. They are likewise quite unstable with respect to color and darken even on standing for a few days.

It has been customary to chemically refine gasolines, naphthas and other hydrocarbon-containing motorfuels to remove the highly unsaturated compounds present therein which are responsible for the above mentioned gum formation. Al-

. though by such treatment an improved motor fuel may be obtained from the standpoint of gum 5) formation and/or deposition, the anti-knock value thereof is generally considerably impairedbecause such chemical treatments not only remove the highly unsaturated bodies deemed responsible for the production-of gums but also remove hydrocarban; of a lesser degree of unsaturation and aromatic compounds which constitute the desirable anti-knock constituents of the motor fuel.

The presence of unsaturated hydrocarbons even those of the type responsible for the formation of gums or gummy products is not undesirable and 5 would even be beneficial were it not for the fact that in the presence of air or oxygen during storage or use they tend to absorb oxygen with the formation of the above mentioned undesirable products, thereby impairing the value and useful 10 ness of the motor fuel.

On account of this, a producer of hydrocarboncontaining motor fuels which contain unsaturated compounds is continuously confronted with the problem of gum formation. 15

Hence, it is an object of our invention to produce high grade motor fuels having no, or a substantially reduced gum-forming tendency and which do not exhibit any tendency to become discolored on standing. 20

It is another object of our invention to present a series of compounds which, when added to hydrocarbon-containing motor fuels which normally tend to form gums during the usual conditions of storage, inhibit or substantially reduce such gum- 25 forming tendencies, and render them stable with respect to color.

Other objects will be apparent from the description of our invention given hereinafter.

According to our invention, the usual chemical 30 purification processes which, as previously stated, tend to remove certain desirable fractions from various motor fuels, may be substantially reduced in intensity or may even be entirely liminated without danger of presenting an inferior quality motor fuel. By adding suitable amounts of the compounds described below, to a motor fuel, it is possible to obtain one containing all the desirable components including unsaturated hydrocarbons without having to consider the possibility of gum 40 formation therein during the usual periods or conditions of storage or use.

We have discovered that certain organic compounds containing an element chosen from the class consisting of arsenic, bismuth, phosphorus 5 i and antimony, if added to any of the motor fuels set forth above, inhibit the formation of gum or reduce the quantity thereof as determined by the previously described copper dish test or by any other test commonly employed for detecting gum formation. Their presence in a motor fuel will also tend to stablize the color thereof as explainedhereinafter.

The organic compounds of arsenic, bismuth. Phosphorus and antimony which we have found to constitute excellent inhibitors or retarders for gum formation in hydrocarbon-containing motor iuels which, in the absence of these compounds. tend to form substantial amounts of gum. are compounds of the type:

wherein R is an aryl or alkoxy-aryl group, R an allryl group, and M an element selected from the group consisting of aresnic, bismuth, and antimony. These compounds are derivatives of tetrahydro-1,4,2,5-dioxdiarsines, dioxdistibines. dioxdibismuthines and dioxdiphosphines. They may be produced for example by condensation oi a primary aryl. or alkoxy-aryl arsine. stilnne. bismuthine or phosphine with an aliphatic aldehide. For complete details of this method of production. reference is made to the Journal of Amer. Chem. Soc., vol. 34 page 1356. Specific compounds is!!- ing within the above identified class are; tetrahydro-3,6-dimethyl-2,5-diphenyl- 1.43.5 dioxdiarsine,

o--cn.cm

CsHsA Met l;

mo. c--o mydro-iflo-dimethyi-zbditolyl-hglsdioudhlllm v o--cn.cn| omcamn 0.84.088

m0. c-o hha ydwMd vl flp y -LLW o-emmm am ncare moi c-o m macdi-np i-zs amp-mam o'--cn.cin|(a) can can; n n1ci.c-'-o mshvmammwi-awmvl-tcammm o-emc-m outcommcucm;

. H10]. C--0 wiwmawmahyl-auipmri-mmmwum.

. o--ca.cm

camat sbcdic mo. c--o umymao ai-nyl-ssdipmyi-taauiormuu.

o--c .cim(n) phosphorus tetrahydro3,o-dimethyl-2,5 diphenyl-l,4,2,5-dioxdiphosphine,

tstrlhydro-3,0-di-n-propyl-2,5 diphenyl-l-4-2-5dioxdiphosphine,

0C H- C 11110!) HsOHC-O Likewise, suitable amounts of mixtures of any or all of the above mentioned compounds or mizgtures of these and compounds of the same class but containing diiierent aryl or alkoxy-aryl substituents may be added to the motor fuel to decrease or inhibit gum formation therein.

Other compounds which we have found to substantially retard or inhibit the formation of gums in hydrocarbon-containing motor fuels are those obtained by condensing an aromatic aldehyde with a primary arsine, stibine, phosphine or hismuthine. These compounds have the general formula: Rr-M-(CHOHR) 2 wherein R is an aryl or slkoxy-aryl group and M is an element of the group consisting oi arsenic, bismuth, phosphorus and antimony. Compounds tailing within this group and which possess excellent gum inhibiting tendencies are: Bis(--hydroxy benzyl) phenylarsihe CsHsAMCHOHCsHsM; bis(-a-hydroxytolyi) tolylarsine HaCCiiI-ImMCHOHCaHiCHah; bis(-a-hydroxybenzyl) phenylstibine CHBSIKCHOKCBHQfl bis(--hydrox'yto1yi) tolylstibine HsCCsHsSb (CHOKCIHACHJ) a; ils(--hydroxybenzyl) phenylbismuthine ctnmi icnoncsm) 1;

bis(--hydroxytolyi) tolylbismuthine HiiCCsHsBi (CHOHCBHACHJ) 2; bis(-a'-hydroxybenzyl) ,phenylphosphi ne canmcrronctm) bis(-a-hydi'oxyifolyli toiylphosphine gsccinmcnonctmcmn,

p -tolyl arsine *(CHOHCGHQfl s; (CHOHCGHQ a.

i l Hixtures oi'canyorall of the above as well as "'mixture'l' ot-aany or Iall of: these and one or more c not the compoundsot the tim formation in various introduced and will continue their stabilizing ac-- tion for days and even months. Their presence in a hydrocarbon-containing motor fuel will prevent the absorption of oxygen by certain of the more unsaturated compounds present which absorption if not inhibited results in the formation of gums or gummy products. This gum formation is a catalytic process, 1. e., the rate of the formation of gums is catalyzed by the gums already present.

The quantity of the material added to the motor fuels for inhibiting the formation of gums may be very small. In general, amounts of the inhibitor varying from 0.001% to 0.1% by weight with respect to the hydrocarbon-containing motor fuel to which they are added, are sufficient to inhibit or substantially retard any gum-forming tendency therein, although in some instances greater or smaller amounts may be added.

The method of adding our inhibitors is exceedingly simple. For example, we may dissolve a quantity of the inhibitor in a small portion of the particular fuel to which it is to be added to form a concentrated solution thereof and then add a sufficient amount of this solution to the fuel to be treated. Or, a suitable amount may be directly added to a large volume of the fuel and dissolved therein by proper agitation. In some instances it may be preferable to dissolve the inhibitor in ahydrocarbon-solublesolvent such as benzol, absolute alcohol or ether, and add suitable amounts of this solution to the motor fuel.

The following examples are illustrative of our invention:

- A pressure distillate having a gravity of 51.1 A. P. I. and which had been given only a mild acid treatment (2% lbs. of H2304 per barrel) followed by redistillation, was found to have a copper dish gum test of '70 mgs. per 100 c. c. without addition of any inhibitor. Upon addition of 0.005% of terahydro-3,6-dimethyl-2,5 diphenyl 1,4,2,6 dioxdiarsine, the gum content decreased at 21 mgs. per 100 c. c.

A second pressure distillate with a gravity of 44.7" A. P. I. and which had been subjected to a treatment with sodium plumbite had an initial copper dish gum test of 872 mgs. per 100 c. c.,

When 0.01% of tetrahydro-3,6-dimethyl-2,5 diphenyl-1,4,2,5 dioxdiarsine was added to 100 c. c. of this distillate, its gum content amounted to only 38 mgs. When this same pressure distillate (100 c. c.) was treated with 0.01% of a gum inhibitor sold under the trade name "Vanoline (para hydroxy diphenyl amine) its gum content was reduced, to only 616 mgs. per 0. c.

The formation of gums in hydrocarbon-containing motor fuels on storage is closely associated with an increase in color intensity of the particular fuel. Our inhibitors are found not only to exert an inhibiting tendency toward gum formation even on storage over prolonged periods of time but also are responsible for the prevention of undesirable color formation. The term inhibiting gum formation" used in the present specification and claims is meant to include the feature of color stabilization. The following example is illustrative of this feature of our invention:

A pressure distillate which had been given a slight acid treatment (2 lbs. of 80% HzSOs per barrel) and which had been subsequently redistilled and doctor treated had an initial color of 1 N. P. A. which after storage of the distillate for a period of 14 days increased to 1% N. P. A. When adding 0.005% of terahydro-3,6-dimethyl- 2,5 diphenyl-1,4,2,5 dioxdiarsine to a fresh 100 c. 0. sample thereof, the color was still better than 1% N. P. A. after standing over a period of 4 months.

As previously stated, the usual chemical refin. ing of the motor fuel, consisting of a treatment withooncentrated sulfuric acid, alkali treating v the acid treated fuel and subsequently water washing may be substantially reduced in intensity or even entirely omitted. However, we prefer to subject the hydrocarbon-containing motor fuel to a treatment with sodium plumbite or an equivalent agent (to remove injurious sulfur compounds) prior to adding our inhibitors.

Although the compounds set forth herein are especially suitable for stabilizing cracked gasolines or blends of cracked and straight run gasolines with respect to the formation of gum, they may be equally well added to other hydrocarboncontaining motor fuels which contain gum-forming constituents. They likewise will act as antioxidants in heavier petroleum fractions such as kerosene, gas oil, lubricating oil and the like.

Gum tests are generally conducted by the previ-. iously mentioned copper dish method, but sometimes by a similar test in which a porcelain dish is used. However, by either method of test, our process is found to reduce or inhibit gum formation.

The term N. P. A. color" used herein relates to a color grade of a liquid obtained by means of the Union Petroleum Calorimeter adapted as a standard of the National Petroleum Association in 1915. A detailed description of the apparatus, method .of test and significance of scale readings may be found in David T. Day-Handbook of Petroleum Ind., 1922, vol. 1, page 665."

The examples and theories set forth herein are not to be considered as limitations upon our process. As to the scope of our invention, reference is hereby made to the appended claims. 4

We claim:

1. In a process for inhibiting gum formation in hydrocarbon-containing motor fuels which normally develop gum during the usual conditions of storage, the step of adding -thereto small amounts of an organic compound of thetype R ac --0 wherein R is an aryl or alkoxy-aryl group, R is an alkyl group and M an element selected from the group consisting of arsenic, bismuth, phosphorus and antimony.

2. Hydrocarbon-containing motor fuels which normally develop gum during the usual conditions of storage and containing an organic compound of the type 0CHR1 wherein R is an aryl or alkoxy-aryl group from the class consisting of phenyl, tolyl, oxyphenyl and oxytolyl groups, R is a lower alkyl group and M an element selected from the group consisting of arsenic, bismuth, phosphorus and antimony.

3. A hydrocarbon motor fuel which normally develops gum during the usual conditions of storage, containing a small percentage in the order of 0.001% to 0.1% of tetrahydro-dialkyl-diaryldioxdistlbine.

4. A hydrocarbon develops gum during 7 age, containing a small percentage in the order of 0.001% to 0.1% of tetrahydro-dialkyl-diaryldioxdlbismuthine.

5. A hydrocarbon motor fuel which normally develops gum during the usual conditions of storage, containing a small percentage in the order of 0.001% to 0.1% of tetrahydro-dialkyl-diaryldioxdiphosphine.

6. Motor fuels containing hydrocarbons which normally develop gum during usual conditions of storage containing a small percentage in the order of 0.001% to 0.1% of an organic compound of the.

type

motor fuel which normally wherein R is an aryl group, R is a lower alkyl group and M is an element from the class consisting of arsenic. bismuth, phosphorous and antimony.

I. Motor fuels containing hydrocarbons which normally develop gum during the usual conditions of storage and containing a smal proportionof tetrahydro,-3,-6-dialkyl-2,5-diphenyl-132,5,- dioxdistibine. 8. Motor fuels containing hydrocarbons which normally develop gum during the usual conditions of storage and containing a small proportionof tetrahyfdro,-3,fi-dialkyl-2,5 diphenyl-1,4,2,5,-di oxdibismuthine.

9. A process for inhibiting gum formation in hydrocarbon-containing motor fuels which normally develop gum during the usual conditions of storage which comprise adding thereto small amounts oi an organic compound-of the type R-M-iCI-IOHR): wherein R is an aryl, or alkoxy-aryl group and Lil anelement selected from the class consisting of arsenic, bismuth, phosphorus and antimony.

10. A hydrocarbon-containing motor fuel which normally develops gum =under oxidizing conditions containing a small amount sufllcient to inhibit such gum formation of the usual conditions of stor- I an organic anaa as compound of the type R-DMCHOHR): wherein R is an .aryl or alkoxy-aryl group and M is an element selected from the class consistin of arsenic, bismuth. phosphorus and antimony.

11. A process for inhibiting gum formation in hydrocarbonntaining motor fuels which normally develop gum during the usual conditions of storage, which comprises adding thereto small amounts of an organic compound of the class consisting of organic compounds of the type wherein R is an aryl or alkoxy-aryl group, R1 an alk'ylgroup and M an element selected from the group consisting of arsenic, bismuth, phosphorus and antimony, andorganlc compounds of the type RM(CHOHR)= wherein R is an aryl or alkoxy-aryl group and M an element selected from. the class consisting of arsenic, bismuth, phosphorus and antimony.

12. Hydrocarbo -containing motor fuels which normally develop gums during the usual conditionsof storage and containing small amounts of a compound of the class consisting of organic compounds of the type n ne-o RM/ \M-R a fim-o wherein R is an aryl or alkoxy-aryl group, R1 an alkyl group and M an element selected from the group consisting of arsenic, bismuth, phosphorus and antimony; and organic compounds of the type R-NUCHOKR): wherein R is an aryl or alkoxy-aryl group and M an element selected from the class consisting of arsenic, bismuth, antimony and phosphorus.

18. A composition according to claim 2 wherein)! is antimony.

14. .A composition according to claim 2 wherein M is antimony, R is a lower alkyl group and R is a phenyl group.

15. A composltlon according to claim 2 wherein M is bismuth.

16. A comm according to claim 2 wherein M lsgbismuth. R is a lower alkyl group and R is aphenylgroup.

- ARTHUR L. BLOUNT. HAROLD G. REIBER.

, CERTIFICATE OF CORRECTION. Patent No; 2,l29,l9L September 6, 1958.

of the above numbered patent requiring correction as follows; Page 2, first column, line 15, for "aresnic" read arsenic; page LIL, firstcolumn, line 51, for "smal" read small; same page, second column, lines 28 to 51, top line of the structural formula, for "R HG-Q read 0 the said Letters Patent should be read with this correction therein that Henry Van Arsdale (Seal) Acting Commissioner of Patents, 

